External Pressure Testing of 4-in-Dia High-Density Polyethylene Pipe1

Abstract

Many of the investigations dealing with the determination of the time-to-failure of high-density polyethylene (HDPE) pipes involve internal pressure tests. HDPE pipe, however, can also be subjected to external pressure such as from underwater laying, vacuum, or burial. For the particular case of uniform external pressure, only a small amount of data detailing the time-to-failure of such pipes is available, and no definitive testing procedure exists. Here, an experimental apparatus and corresponding testing procedure are developed to explore remedies for this situation. On the basis of the data thus obtained, a three-coefficient equation relating time, temperature, and pressure is generated. The failure predictions from this design basis equation are in good agreement with the available data existing in the literature.